Originally Posted by
Boraxxe
The scene is focused on Bilbo as he discovers that he has, in fact, kept the envelope with the ring in his pocket instead of placing it on the mantel.
Gandalf looks like he is reacting to someone simulating Bilbo on the sound stage and the simulation is slightly off-location to where the Bilbo we see on-screen is actually at.
One of the few directorial/editorial goofs.
They used forced perspective quite a bit in that movie, for the scenes where hobbits and normal sized characters were acting together in the same frame. It's an old Hollywood trick, placing one actor much closer to the camera than the other, but making it appear that they are standing right next to each other. That way the actor closest to the camera appears much larger. I would imagine that may have happened in the scene you're referring to, McKellen probably momentarily forgot where his eyes should be focused, and the fault was missed in editing.
I agree that Ian McKellen's portrayal of Gandalf was spot on, I don't think I could ever picture anyone else as Gandalf now.
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